We implemented multiparticle detection system (MPD), which enabled the improvement of sensitivity of immunoassays (IA/MPD) by about a factor 500 down to 1 fg/ml. The proposed gas based implementation of MPD will permit the throughput increase about 10-fold, as well as some further increase of sensitivity. Furthermore, the proposed detection system is almost ideal for the diagnostic proteomics applications. We will implement gas based MPD Readers to enhanced P-chips (P-chips/MPD). [unreadable] [unreadable] However, even more important to biomedical community will be the enabling properties of new detector. It will enable a proprietary system for studies of protein-protein interactions that is about hundred times more sensitive than current techniques. This protein-protein interaction quantification system capitalizes on MPD's exquisite instrumental sensitivity to enable the highest sensitivity detection and reasonable throughput even for low abundance proteins. The ultra high sensitivity and very large dynamic range combine to make Auger Electrons Mediated Energy Transfer method (AEMET) far superior to other methods of functional proteomics. The particular properties of this process permit to estimate the distance from "donor" to "acceptor" molecule. In another implementation, it permits to elucidate the integrity and topological configuration of a particular macromolecule. With appropriate substrate, it permits to very specifically measure the cleavage of target macromolecules by appropriate enzymes. [unreadable] [unreadable] The most important element of the development proposed in this proposal is the innovative gas based detector of electrons, which permits in to measure in convenient 96 well format interactions of many proteins concurrently. It is based on detection of electrons in gas and will require extensive development of electronics and software. [unreadable] [unreadable]